Keyboard transmitter



y 10, 1956 E. F. KLEINSCHMIDT ETAL 2,754,364

KEYBOARD TRANSMITTER Filed June 14, 1951 3 Sheets-Sheet 1 1- lhl 0INVENTORS EDWARD E KLEmscHMwT CARL. R ANDERSON y 10, 1956 E. F.KLEINSCHMIDT EI'AL 2,754,364

KEYBOARD TRANSMITTER Filed June 14, 1951 3 Sheets-Sheet 2 INVENTORSEDWARD F. KLEINSCHMIDT CARL P. ANDERSON MM w ATTO RN EY-S y 10, 1956 E-KLEINSCHMIDT ETAL 2,754,364

KEYBOARD TRANSMITTER 3 Sheets-Sheet 5 Filed June 14, 1951 INVENTORSEDWARD E Kuzmscumm' CARI. I? ANDERSON r/M ww m AT TO RN EYS UnitedStates Patent O KEYBOARD TRANSMITTER Edward F. Kleinschmidt, Wilmette,and Carl P. Anderson,

Highland Park, 111., assignors to Kleinschmidt Laboratories, Inc.,Deerfield, Ill., a corporation of Delaware Application June 14, 1951,Serial No. 231,554

24 Claims. (Cl. 178-79) This invention relates to transmitters forprinting telegraph systems and more particularly to transmitters whichare controlled by and integral with an associated keyboard.

The preferred embodiment of this invention is adapted for use with atelegraph system of the start-stop type, wherein the signals comprisepermutations of impulses corresponding to two difierent line conditionsextending throughout a definite number of time intervals. The selectingintervals or impulses of each signal are preceded by a starting intervalor impulse of uniform line condition and followed by a stopping or restimpulse or interval which is always the same and of opposite linecondition from that of the starting interval or impulse.

The two different line conditions are customarily referred to asintervals during which marking or spacing impulses are transmitted. Themarking impulses correspond to intervals during which current istransmitted and the spacing impulses correspond to intervals duringwhich current is not transmitted. Usually the start interval consists ofa spacing impulse and the stop or rest interval consists of a markingimpulse. In certain instances polarized systems are used wherein thetelegraph signals are formed by reversing the direction of current flowinstead of interrupting the current flow. Thus the marking impulse willcomprise a current flow in one direction and the spacing impulse a flowof current equal in value but in the opposite direction. Ordinarily theBaudot code is used in telegraph printer systems. It consists of a startpulse, five permutated impulses, and a stop pulse. Other systems use asix or seven unit code in addition to the start and stop impulses.

In signal transmitters for printing telegraph apparatus it has becomeincreasingly important, as the speed of operation increases, to providemechanisms that will accurately space the signals according to a patternand prevent any bounce of the electrical contacts so that perfect makeand break or positive and negative signals may be transmitted at highspeed. The transmitters of the prior art, such as the multi-contact typetransmitter disclosed in U. S. Patent No. 2,135,377 to Dirkes et al.,worked fairly satisfactorily with telegraph printers limited toreceiving fifty or sixty words per minute. However because of thetremendous demand for the use of telegraph lines, and because of therapid advances made in the associated arts and the need for increasingthe speed of conveying intelligence in regard thereto, such a rate ofspeed is no longer satisfactory particularly where the machines are usedby the Armed Forces of the United States. Accordingly we have developeda keyboard transmitter which operates with a telegraph printer whichwill print one hundred words per minute and which has been accepted bythe Signal Corps of the United States Anny as its standard telegraphprinter.

In telegraph printers in the past the transmitter comprised either adistributor having a rotating armor brush which passed over a series ofcontact segments, or a group of contact springs equal in number to theimpulse 2,754,364 Patented July 10, 1956 units of the particular code inuse. For many reasons such transmitters were unsatisfactory especiallywhen operated at high speeds. In the distributor type the brush was aconstant source of trouble, and in the multicontact type the manycontacts required constant adjusting and introduced difficulties inproducing accurately spaced signals free from the effect of bouncingcontacts,

We have overcome the difficulties inherent in such transmitters byproviding for page and tape printers a single pair of positivelyactuated contacts of novel antibounce construction, having a singlecontact operating bail which is common to all of the code selectinglevers. With this construction we have eliminated the necessity ofconstantly adjusting many sets of contacts and the poorly spaced signalsso frequently caused thereby. It has also been customary in the priorart transmitters to have the rotatable member make a complete revolutionfor each code combination of impulses transmitted. When faster operationwas desired the entire machine was speeded up to make the rotatablemember turn at a higher speed with the result that the machine partsbecame unable to withstand the increased strain and wear. We haveovercome the above problem by increasing the number of codetransmissions made in one revolution, thus maintaining reasonable speedswhile accomplishing more work per revolution. This has been accomplishedby providing relatively large cam sections each having two or more camlobes so that at least two characters may be transmitted in the courseof one complete revolution of the cam sections as will be more fullyexplained hereinafter. Thus, without materially increasing rotationalspeeds and strains the output and efiiciency of our transmitter isgreatly increased by taking advantage of the increased lengths andperipheral speeds of the cam sections.

Accordingly, it is'a primary object of this invention to provide asignal transmitting mechanism in which the transmitting contacts areoperated by a positive motion under control of a transmitting cam unitand to provide means for accurately spacing the signals as Well as toprevent bounce when a contact is made or broken.

Another important object of our invention is to provide a keyboardtransmitter in which the speed of operation has been greatly increasedby transmitting the code combination of impulses representing onecharacter during one-half revolution or less of the rotatable member.This arrangement permits a greatly increased output without increasingthe speed of rotation of the mechanisms involved. V

A further object of this invention is to provide a keyboard controlledtransmitting mechanism of great simplicity, improved efficiency andprolonged life which will transmit to a telegraph circuit combinationsof code impulses corresponding to and representing actuated key levers.

A still further object of this invention is to greatly simplify theconstruction, operation, and maintenance of a keyboard and transmitterby providing a single set of contacts for controlling the linecondition, thereby eliminating the formerly used plurality oftransmitting contacts.

Another object of this invention is to provide a keyboard andtransmitter having electrical contacts operated by a set of levershaving two different mechanical motions and sequentially operated byone-half revolution or less of a rotatable member to send currentimpulses corresponding to an actuated key lever.

Another object of this invention is to provide a keyboard andtransmitter including a universal bar operable when any key is depressedto start the transmitter operating and returned, as soon as the key isreleased, to its normal position by spring means to insure its 3readiness for a subsequent operation when the next operated key isdepressed.

A further object of the invention is to provide a nonrepeat means toprevent repeated transmittal of the same code group if a key is helddepressed for too long a time.

A still further object of the invention is to provide a mechanism torender the non-repeat means inefiective when the space-bar is actuatedso that the spacing operation will be repeated until the space-bar is released.

Another object of this invention is to greatly reduce the manufacturingand maintenance costs of telegraph printers by designing certain of theparts for interchangeable use in other types of printing mechanisms aswell as in various other portions of the same machine so that such partsmay be manufactured in large quantities and their cost therebyminimized. In particular the same selecting control levers are used andthe same operating principles are applied in the signal transmittingapparatus as are used in the selector mechanism disclosed in copendingapplication Serial Number 190,359 filed October 16, 1950, by Edward F.Kleinschmidt.

A more complete and thorough understanding of the invention may be hadfrom the following detailed description in conjunction with theaccompanying drawings forming a part of this specification showingpreferred embodiments thereof in which like reference charactersindicate like parts and in which:

Figure 1 is an end elevation of a preferred embodiment of the invention;

Figure 2 is a perspective view of the transmitter and code bars of theinvention;

Figure 3 is a fragmentary elevation showing the essential parts inposition to transmit a marking impulse;

Figure 4 is similar to Figure 3 but positioned to send a spacingimpulse;

Figure 5 is a front elevation partly in section of the transmitter ofthe invention;

Figures 6, 7, and 8 are vertical sectional views of a portion of theapparatus showing various operative positions assumed by the mechanism;and

Figure 9 is a cross sectional view showing the details of the contactmechanism.

In order to simplify the drawings, a considerable portion of the framestructure has been omitted. Also various springs which would normally beemployed for restoring various operating parts to normal have beenomitted or shown schematically in order to avoid complicating thedrawings. It is to be understood, however, that suitable supportingmeans may be provided for the transmitter mechanism, and that suitablesprings may be provided wherever necessary for assisting in theoperation of parts and for restoring the various parts to normal.

Keyboard transmitter The preferred embodiment of this invention utilizesan electrical transmitting device comprising a single set of contacts,instead of the usual distributor member, operated by a rotatable camdrum which is released for one-half revolution at a time by theactuation of any of the keys. During this one-half revolution of the camdrum the contacts are actuated to transmit a code group of impulseswhich represent the character of the key actuated. The rotatable cammember is stopped and started for each character code group transmittedand a non-repeat mechanism is provided to prevent repeated transmittalof the same code group if the key is held depressed for too long a time.However, another mechanism is provided to render the non-repeatmechanism inoperative when the space-bar is actuated so that the spacingoperation will be repeated until the space-bar is released. Therotatable cam drum is normally prevented.

from rotating by a stop latch which is controlled by a v is shifted, isrocked into or out of position above the universal bar that operateseach time a key or the spacebar is depressed, and means are provided forregulating the amount of movement between the universal bar and the stoplatch. Other means controlled by the cam drum during its rotation returnthe stop latch to its normal position so that it will be effective tostop the rotation of the cam drum upon its completing one-halfrevolution. The keys, key levers and transmitter are assembled as acomplete unit on a frame which is secured to the printer frame in amanner to permit its easy removal to allow the interchange of keyboardand printer units.

The rotatable cam drum actuates selector levers in one of two varietiesof motion to open or close the associated electrical contacts. Theseselector levers or fingers as well as certain other parts are identicalto parts disclosed in copending application Serial No. 190,359, citedhereinbefore, and the same principles of operation are applied in bothmechanisms. These same parts are designed for use in various other typesof tape and page printers, and the manufacturing and maintenance costsof all such mechanisms using these same parts are greatly reducedbecause quantity production methods may be used to produce theinterchangeable parts.

The preferred embodiment of this invention utilizes an electricaltransmitting device selectively responsive to the actuation of fingerkeys 50 (Fig. 1) arranged substantially like the keys -of the ordinarytypewriter and attached to the upturned ends of key or control levers 52which pass thru aligning and guiding slots in a comb member 54, keyboardframe member 56 and a rear frame comb member 58 (see Fig. 1'). Thekeyboard may be removably secured to the printer frame in any suitablemanner. Springs 60 are secured between the key levers 52 and a turnedover portion of comb member 58 and cooperate with notches in the upperedge of the key levers to position them in the slots and to pull themupwardly in a manner well known in the art. A stop strip 62 is securedon the back of comb 54 and above the key levers 52 to restrain the keylevers in their upward movement. When a key 50 is depressed against thetension of a spring 60 the associated key lever 52 positions a series ofpermutation bars 64, 66, 68, 70 and Y 72 in various combinations whichrepresent, according to a predetermined arrangement, the characterassigned to the particular key 50 depressed. The permutation bars 64,66, 68, 70 and 72 are provided with beveled notches 74 (Fig. 2) cuttherein in a manner well known in the art which allow the bars to becammed into position by the operation of a key lever 52.

The permutation bars have elongated slots 76 at their ends whichsurround mounting studs 78, secured in the frame in any suitable mannerand provided with spacing collars 80 for positioning the bars, so thatthe bars are free to move transversely under the key levers 52 to eitherone of two positions. The notches 74 in each bar have variously arrangedinclined faces, one such face being provided on each bar for each keylever 52, so that each bar is adapted to be moved to its right handposition by some of the keys and to its left hand position by the otherkeys to set the bars into different combinations. A universal bar 82mounted adjacent the first permutation bar 64 is provided with notches84, each having a similarly inclined face, so that the universal bar 82is always moved to its right hand position whenever any key 50 isactuated.

Each permutation bar is provided at its right end with a notch 86 (Fig.4) in its upper edge which engages the lower end of a correspondingblocking latch 88 as shown in Fig. 2. The five blocking latches orlevers 88 extend upwardly and are mounted upon a common pivotal support90 secured to the frame 56. The blocking latches 88 control a set ofcontact operating selector levers 92 and each is provided with a hookedlug 94 at its upper end which, as the associated permutation bar hookedend 96 of the corresponding selector lever 92 to block or unblock thelever and' thereby" determine the subsequent movement imparted to thelever by the cam with which it is associated as will be later explained.A bracket 98 having a turned up comb portion for supporting and guidingthe blocking latches 88-is secured by some suitable means as screws 99to the keyboard frame member 56.

A transmitter cam shaft 100 is journalled in a boss 102 of the framemember 56 and connected through a friction clutch 10-4, of a type wellknown in the art, to a shaft 106 (see Fig. 1) rotatably connected to aconstantly rotating drive shaft of an electric motor (not shown). Themotor is provided with a suitable governor for maintaining the motorspeed constant, the governor being provided with suitable means by whichthe speed of the motor may be regulated. Such a governor is disclosed incopending application Serial Number 160,687, filed May 8, 1950, by CarlP. Anderson, now U. S. Patent No. 2,617,904.

Secured to the camshaft 160 (Fig. is a cam drum 108 provided with aseries of cam sections arranged helically around the drum tosuccessively engage and operate the selector levers 92. In theparticular embodiment of the invention herein disclosed, seven selectorlevers 92 are provided, one for the start impulse, five for the codeimpulses, and one for the stop impulse. A cam section is provided foreach of the selector levers 92, and in addition a restoring cam sectionand a latch cam section are provided for purposes hereinafter disclosed.It is to be understood that the number of permutation bars, blockinglevers 88, selector levers 92, and cam sections is not limited to thenumber disclosed herein but that the number is variable and determinedby the number of current impulses comprising the particular code in use.Each of the cam sections has a pair of diametrically opposed raisedportions or cam lobes 110 which, due to the helical arrangement of thecam sections on the cam drum 108, successively engage their associatedselector levers 92 once during each onehalf revolution of the cam drum.This in turn permits the transmittal of code signals for two charactersduring each revolution of the cam drum 108. It will be understood, ofcourse, that it is possible to transmit more than two characters perrevolution of the cam drum by providing more than two cam lobes 110 for.each cam section.

Referring to Figures 2 and 5-8, the mechanism for controlling rotationof the cam drum during signal transmission, including a device forblocking repeat transmissions by inadvertent holding down of a keylever, and a device for disenabling the repeat blocking means bydepressing the space bar for repeat transmission of spaces, will bedescribed. The transmitter camshaft 100 and cam drum 1438 are normallyheld against rotatablemovement by a latch or yieldable stop 112 which ispivoted on pivot post 114 and has shoulder 116 arranged to engage eitherof the two stops 118 formed in the front cam section of the cam drum 108preventing drum rotation and causing friction clutch 104 to slip. Aspring 12% fastened between the machine frame and the latch 112 tends tobias the latch out of the path of stop 118 and thereby permit the camdrum 108 to rotate, but latch movement under spring bias is normallyrestrained by the end 121 of the latch which is turned sideways andengages the blocking lug 122 of a clutch release lever 124 pivoted on astud 126 secured in the keyboard frame 56. An adjusting screw 128 is inthreaded engagement with the clutch release lever 124 and the end of thescrew engages the universal bar 82 to permit the lever 124 to beadjusted relative to the universal bar 82. A spring 138 fastened betweena turned over edge 132 of the lever 124 and the frame 56 tends to forcethe universal bar 82 to the left and to maintain the blocking lug 122 oflever 124 under the end 121 ofthe yieldable stop 112 as shown in Figs: 2and 5 of the drawings.

The adjusting screw 128 permits the release lever-124 to be adjustedrelative to the universal bar 82 whereby the amount of movement of theuniversal bar 82 necessary to eifect the operation of the tripping meansmay-be made variable and extremely slight. A repeat blocking lever 136is pivoted on pin 126 with the clutch release lever 124 and also has ablocking lug 134 substantially coextensive with the release leverblocking lug 122 but extending a few thousandths of an inch higher thanthe top of lug 122. Locking lever 136 is biased by a spring 138connected between an car 140 on the blocking lever and an car 142 on therelease lever 124 so its blocking lug 134 normally engages the adjacentside of blocking lug 122, shown in Figure 5.

As explained above, when a key 50 is depressed its associated key lever52 engages the inclined face in a notch in the universal bar 82 whichinvariably moves to the right. This movement of the universal bar 82pivots the release lever 124 together with the blocking lever 136counterclockwise against the tension of spring 130. The blocking lug 122of release lever 124 moves to the left away from blocking engagementwith the yieldable stop latch end 121. Since the blocking lug 134 of therepeat blocking lever 136 extends slightly above blocking lug 122,continued movement of lever 136 to the left is prevented by engagementwith the side face of the stop latch end 121, as shown in Figure 7,however its spring connection with the release lever continues to biasthe repeat blocking lever 136 counterclockwise. When blocking lug 122has been moved out from under the stop latch end 121, the stop latch 112can move clockwise under the bias of spring a short distance which whilestill maintaining engagement with and preventing further clockwisemovement of the repeat blocking lever 136 is sufficient to remove theshoulder 116 from engagement with the stop 118 on the cam drum 108 whichwill rotate due to its connection thru the friction clutch 104 to theconstantly rotating motor. As the cams on the cam drum 108 are double,i. e., have diametrally disposed raised portions, a transmission of codesignals is accomplished during each one-half of a cam drum revolution.The stop latch 112 as will now be described, is arranged to beautomatically reset to stop the drum rotation at the end of eachone-half revolution.

When the five code cams have completed their functions cycle, describedhereinafter, a cam follower 190 on a locking bail 186 integral with thestop latch 112, is engaged by a restoring cam lobe 110 on the cam drum(Figure 5) causing a counterclockwise pivoting of the latch 112. Aslatch 112 moves counterclockwise against the bias of spring 129 itsshoulder 116 is moved into the path of a cam drum stop 118 to thereuponstop the rotation of the cam drum by friction clutch 104. Since thereare two restoring cam lobes and two cam drum stops the function justdescribed occurs during each onelralf revolution of the drum. Restoringmovement of the stop latch 112 raises its end 121 above the top ofblocking lug 122 on the clutch release lever 124. If the depressed key56 has been released by the operator the spring will move release lever124 in a clockwise direction on the pivot post 126 since the universalbar under bias of a spring 192, secured between the machine frame andthe universal bar 82, is moved to the left to a normal position wheneverthe depressed key is released andregardless of theposition of latch 112and lever 124. Clockwise movement of lever 124 upon raising of the stoplatch end 121 will again place blocking lug 122 under end 121 to holdthe stop latch 112 in position to lock the cam drum 108 against furtherrotation. The arrangement of the universal bar spring 192 makes theuniversal bar operation more positive since it is not dependent formovement upon lifting of the latch 112 near the completion of rotationof the cam shaft. Furthermore an early return of the universal bar 82 toits normal position assures its readiness for a subsequent operation ofanother key. Depression of a subsequent key will again move theuniversal bar 82 to the right pivoting the release lever 124-counterclockwise to release its blocking action on the stop latch 112again initiating cam drum rotation.

Repeat transmission block A 'second or repeat transmission of the sameset of code signals cannot be accomplished by holding the key in adepressed position. Such repeat signals are prevented by the repeatblocking lever 136. If key 50 is still depressed when the transmittercompletes a code signal transmission, the universal bar 82 will still bein its operated position and the blocking lug 122 of the release lever124 will be maintained in its operated position as shown in Figure 7. Asthe end 121 of the stop latch 112 is raised by the action of therestoring cam, as explained above, the repeat block lever 136 will nolonger be engaged by latch end 121 hence it will be pulledcounterclockwise by spring 138 to the position shown in Figure 8 whichpositions the blocking lug 134 under the end 121 of stop latch 112 toprevent the stop latch end 121 from moving downwardly under spring biasto release its stop shoulder 116 from the cam drum stop 118. Asubsequent release of the key will permit springs 192 and 136 to returnthe universal bar together with the release lever 124 to their normalpositions, as shown in Figure 5, with the end 121 of stop latch 112again resting on the release lever blocking lug 122. It is' thus seenthat to accomplish a repeat transmission of a character it will benecessary to release the operated key 50 and then reoperate it to startanother cycle of transmission operation similar to that described in theforegoing paragraphs.

Repeat transmission for space bar The space bar 194 (Figure 1) issupported by arms 196, secured thereto in any suitable manner, which arepivoted upon a rod 198 fastened on the cone 54. A space bar operatingbar 290 is slidably pivoted at one end 202 on one arm 196 and isotherwise positioned and mounted like any key bar 52 and performssimilar functions. When space bar 194 is depressed the bar 200 moves theuniversal bar 82 and permutation bar 68 to the right and bars 64, 66, 70and 72 to the left in accordance with the Baudot code. This will permitthe cam drum 108 to rotate to transmit the proper code signals for thespacing operation. The operation will be the same as described aboveuntil the restoring cam operates the restoring lever 186 to raise theend 121 of the latch 112. When the space bar operating bar 200 wasdepressed it engaged an off-set end 204, Figures 5 through 8, of arepeat lever 206 and moved it counterclockwise (Figure 6) about thepivot 2138. This action raises the toe 210 of a leg portion of lever 206into engagement with an car 212 integrally formed on the repeat blockinglever 136 and will thus hold the repeat blocking lever against the pullof spring 138 when the end 121 of stop latch, 112 is raised away fromholding engagement with the repeat blocking lug 134 by action of therestoring cam. Consequently, when the restoring cam lobe passes the camfollower 191) the latch 112 will again be operated by the pull of spring1213 and its end 121 will again be positioned between the blocking lugs122 and 134 as seen in Figure 6. The spacing operation will be repeatedso'long as thespaced bar 194 is held depressed and when it is releasedthe universal bar 82is moved to its left by the stored energy of spring192 and spring 130 will pivot the lever 124 to again place the blockinglug 122 under the latch end 121 to hold the latch 112 in a stop positionthus preventing continued rotation of the cam drum 108.

The selector levers 92 each have upturned portions 144 and 146 (Figs. 3and 4) adjacent their respective ends, a cam follower 148, and dependingportions 150 and 152 which fit around a squared shoe 153 on pivot post114. A spring 154 is secured between the machine frame and the portion152 of each lever 92 to normally hold the lever against the shoe 153 onthe pivot post 114 and a stop 156 secured to frame 56. The turned upportions 144 and 146 engage and position a contact bail 158 pivoted at160 and provided with a pair of contacts 162 and 164 which cooperatewith contacts 166 and 168 respectively to control the condition of theline circuit of the associated telegraph system.

Contact supports 176 and 172 (Fig. 9) are adjustable screws engagingterminals 173 fitted into an insulated supporting block 174. Thecontacts 166 and 168 are plungers which are pressed forward by coiledsprings 175 positioned between shoulders 176 formed on the contactplungers and guide plugs 177 screwed into the upper portion of thecontact supports and 172. The contact supports may be turned in and outuntil the contacts 166 and 168 are in the proper relationship with thecontacts 162 and 164 and set screws 178, only one of which is shown, maybe set to maintain the adjustment. It is to be noted that the contactbail 158 is not biased or spring pressed in one direction as is usual inmechanism of this type but is operated solely by positive mechanicalmeans which assures positive operation in the manner desired. Thecontact bail 158 is engaged near its ends by the upturned portions 144and 146 of the transmitter levers respectively with just suflicientclearance to permit the levers and contact bail to pivot under thecontrol of blocking levers 88 and cam drum 108.

In mechanically operated transmitting contacts, particularly where suchcontact mechanisms are operated at high speeds as required in printingtelegraph signal transmitting apparatus, the prevention of contactbounce has presented serious difiiculties. The contact mechanism hereindisclosed overcomes these dilficulties by the use of the novelconstruction of contact mechanism which is described as follows: Therocking contact bail 158 is positively pressed by selector levers 92against plunger contact members 166 and 168 which are spring pressed andslidably and frictionally mounted in adjusting screws. Exhaustive testshave demonstrated that the friction of the contact plunger in itsbearing will absorb any bounce due to impact of the rocking contact bail158 against contact plungers 166 and 168.

As the contact 162 'or 164 is raised and meets its associated contact166 or 168 the initial shock of meeting is cushioned or absorbed by thecoiled spring which compresses as the plunger moves upwardly into theguide plug 177. The distance which the contact on the bail 158 movesafter it first engages its associated contact until it reaches its fullextent of movement must be interrelated with the initial tension of thespring 175 and the adjusted position of the contact support 170 or 172so that the contacts will remain in engagement throughout theirprescribed movement without any intermittent opening and closing of thecontacts which has become known as bounce. The initial tension of spring175 is fixed by its being positioned between the shoulder 176 on thecontactand the guide plug 177. This tension is not changed when thecontact support is adjusted in the block 174 to determine the normalposition of the con- ;tact'166 or 168 in relation to the associatedcontacts 162 or 164, and is sufiicient to cause the contact to remain inengagement with the bail contact during its upward movement. The contactarrangement disclosed prevents any undesired or unauthorized opening ofthe con- 7 tacts dueto bouncesuch as is usual in spring pressed contactsbecause the mechanical arrangement is such that the contacts, onceclosed, are" held firmly together until the next operation begins.

In the embodiment of the invention shown herein we provide two sets ofcontacts for use in a telegraph system of the polarized current type. Insuch a system the contacts 162 and 164 are connected in parallel bymeans of the flexible conductor 179 (Figs; 3' and 4) and terminal 188 tothe telegraph line, and the contact 166 is connected to a current sourceof a certain polarity while the contact 168 is connected to a currentsource having the opposite polarity to that connected to contact 166.Thus when contacts 162 and 166 are'engaged current of the first polarityis connected tothe telegraph line and when contacts 164 and 168 areengaged current of the opposite polarity is connected to the line. Thecontact bail 158 is of sufiicient width to be operated by each of theselector levers 92' which are capable of motion in two directions underthe control of the blocking levers 88 and cam drum 108 to determinewhich contacts will be engaged. Thus, if a blocking lever 88 blocks theend 96 of its associated lever 92 (Fig. 3) as the latter is engaged byits cam, the opposite end will raise upon the pivot post 114 to engagecontacts 164' and 168. If the blocking lever 88 does not block the end96 of the selector lever 92 (Fig. 4), it will pivot upon the shoe 153and post 114 and raise the end 144 to close contacts 162 and 166. Whenthe transmitter is associated with a system having only one source ofcurrent the contact 166 or the external electrical connections tocontact 166 will be omitted as is well known in the art.

In a polarized system it is necessary that one or the other of themovable contacts be in engagement with its associated contact at alltimes to maintain current of the proper polarity on the line andtherefore cams and selector levers 92 must be provided for the start andstop positions of the transmitter. The front or first cam section inFig. 5 cooperates with the latch 112; the second cam operates arestoring lever, to be described; the third, fourth, fifth, sixth, andseventh'cams operate the five code selector levers; the eighthcamcontrols the start selector lever and the ninth cam operates the stopselector lever. In the stop or rest position the cam lobe 110 of thestop cam section raises the associated stop selector lever 92 and as theend of the lever is always blocked by a fixed catch 182 (Fig. 1') thelever will pivot about its right end and its l efthand upturned portion146 will engage the left end of contact bail 158 to close contacts 164and 168 to connect a marking'current to the telegraph line.

The first movement of the cam drum 108 causes the lobe 110 of the stopcam t'o disengage the cam follower 148 of the stop selector lever 92 andimmediately thereafter the lobe 110 of the starfcam engages the camfollower 148 of the starfselector lever 92 and as there is no blockingor latching member provided for the start selector lever it willinvariably pivot on post 114 raising its right (Fig. 4) or unblocked endto cause the up-turned portion 144 to press the contact bail 158upwardly, as in Fig. 4. Bail 158 will pivot'at 160 to close contacts 162and 166 and open contacts 164 and 168 and thereby place the associatedtelegraph line in a start condition. The cam drum 108 continues torotate and successively operates the five code selector levers 92 tocontrol the position of the contact bail 158 in' accordance with theblocked or unblocked condition of the levers.

Thus if the key 50 which corresponds to the letter Y is depressedpermutation bars 64, 68, and 72 will be moved to the right and bars 66and 70 will be moved to the left. The blocking levers or latches 88associated with the respective bars assume corresponding positions withthe first, third, and fifth levers in their latching or blockingpositionand the second and fourth in their un-' blocking position. Theblocking levers 88 are held in their respective positions by a knifeedge 184 (Figs. 1 and 5) formed on the end of the restoring locking.bail 186 which is an integrally formed angularly displaced portion ofthe latch 112. The knifedge' 184*i's moved by the pivotal movement ofthe latch 112 into-engagement with the ears 188 on the ends of therespective blocking levers 88 to hold them in position until a completecode is sent by the transmitter. key 50 will not be efiective to set upanother code as the blocking levers 88 cannot move until the code forthe first character is completely transmitted.

As the cam drum 108 continues to rotate the first code cam engages thecam follower 148 on the first code selector lever 92 which has its rightend blocked by the first latch 88 (Fig. 3) so as its cam follower 148rides up on the lobe 110 of the cam the right end of the lever Will beheld down to act as a pivot whereby the portion 146 will press thecontact bail 158 upwardly to close contacts 164 and 168 and opencontacts 162 and 166 which were previously closed by the operation ofthe start selector lever 92. By the time the cam follower 148 of thefirst code selector lever 92 is engaged by its associated cam the camlobe 110 for the start lever has passed beyond the start cam follower sothe contact bail 158 is free to move under the influence of the firstcode lever. The second code lever 92 does not have its end blocked (seeFig. 4) and therefore pivots on the post 114 to raise the right end ofcontact bail 158 to open contacts 164 and 168 and close contacts 162 and166 to place the line in a space condition. As the code levers 92 aresuccessively engaged they will operate the transmitter contacts toalternatively (for the letter Y) place marking or spacing current (orcurrent or no-current) on the telegraph line inaccordance with theblocked or unblocked condition of the levers. Immediately upon theoperation of the'final, in this case the fifth, code selector lever 92'the restoring cam lobe 110 engages the cam follower (Figs. 2 and 5) onthe restoring locking bail 186 whichpivots on post 114 and disengagesthe knife edge 184 from the ears 188 of the blocking levers 88 so thatthey may be moved by the depression of a key 59 to set up thetransmitter for the sending of another code signal; The restoring bail186, as pre-' viously described, is integrally formed with latch 112 andas latch 112 is pivoted by the restoring bail its shoulder 116 is movedinto the path of the cam stop 118 to stop the rotation of the cam stop108 upon their'engagement'. At this time the stopselector lever 92 is inan operated position and contacts 164 and 168 are closed to' place theline in a mark condition.

From the foregoingdescription it will. be apparent'that the novelinvention disclosed herein provides. a reliable keyboard transmittermechanism operating at'a comparatively slow speed but transmitting codesignals at high speed. At the same time the transmitter is compact andvery durable and provides a novel'construction and arrangement ofelements which overcome to a large extent the difliculties and drawbacksof the prior art.

The invention may be embodied in other specific forms without departingfrom the'spirit or essential characteristics thereof. The presentembodiment is therefore to be considered in all respects as illustrativeand not restrictive the scope of the invention being indicated bythe-appended claims rather than by the foregoing description,

and all' changes which come Within the meaning and range of equivalencyof the claims are therefore intended to be embraced therein.

What is claimed and desired to be securedby United The depression ofanother said contacts away from each other, means operable by saidrotatable member to sequentially actuate said contact operating leversin one of said oppositely directed paths of motion, and means controlledby the actuation of one of said key levers to restrain the movement of aportion of said contact operating levers in said first path of motionand to compel the movement thereof in a second path of motion wherebysaid pair of contacts is actuated in a predetermined manner tocorrespond to the actuated key ever.

2. In a telegraph keyboard transmitter, a set of key levers, a universalbar invariably operated on the actuation of any one of said key levers,a rotatable mechanism, wholly mechanical linkage means, including saiduniversal bar, structurally cooperating with said rotatable mechanism,responsive to the depression of one of said key levers .to initiate therotation of said rotatable mechanism, means operated by said rotatablemechanism to stop the rotation thereof at the end of each one-halfrevolution, and resilient means efiective upon the release of theactuated key lever to restore said universal bar to its normal position.

3. In a telegraph transmitter, a group of control levers, a rotatablemember with a plurality of diametrally double cams prearranged thereon,means for rotating said member, means for rendering said last mentionedmeans operable, a plurality of rockable blocking latch memberscontrolled by actuation of one of said control levers, a pair of currentcontrolling contacts, a pivotable bail for supporting one of saidcontacts, a plurality of levers the movement of each of which iscontrolled by an individual one of said blocking latch members and whichare sequentially engaged by the cams of said rotatable member during therotation for positively operating said contact bail to engage and todisengage said contacts in combinations according to a code combinationfor the actuated control lever, and means associated with said rotatablemember for stopping rotation thereof at the end of each one-halfrevolution after the code combination has been transmitted.

4. A device as defined in claim 3, wherein said contact bail operatinglevers are so mounted as to pivot about either of two points thereonupon engagement by said rotatable member, the pivot point depending uponwhether said levers are blocked or unblocked by said rockable blockingmembers.

5. In a device as defined in claim 3, said contact bail operating levershaving means adjacent the respective ends of said levers for positivelyoperating said contact and preventing unauthorized movement thereof.

6. A device as defined in claim 3, wherein said contact bail is commonto all of said contact bail operating levers.

7. A device as defined in claim 3, wherein said contact bail is equal inwidth to the combined widths of said contact bail operating levers andthe total width of the spaces between each adjacent pair of said contactbail operating levers.

8. In a telegraph'transmitter, a group of key levers, a universal baradapted to be operated by any one of said key levers, a rotatablemechanism, means controlled by said universal bar upon operation by akey lever to initiate the rotation of said rotatable mechanism, meansoperated by said rotatable mechanism to stop the rotation thereof at theend of each one-half revolution, and means controlled by said rotatablemechanism and cooperating with said universal bar to prevent subsequentoperation of a key lever during the rotation of the rotatable mechanism.

9. In a telegraph transmitter, a rotatable member, means for rotatingsaid member, a plurality of rockable blocking members, a pair ofcontacts, a set of contact operating levershaving two varieties ofmotion controlled by'said blocking members in predetermined combinations and sequentially operated by said rotatable member to engagesaid contacts, said contacts being common to all of said contactoperating levers, and resilient means operable to maintain said contactsin engagement.

10. In a telegraph keyboard, a set of key levers, a universal barinvariably operated on the actuation of any one of said key levers, apower driven rotatable member, a yieldable stop, a first blocking memberfor said a stop, means including said yieldable stop and said firstblocking member for holding said rotatable member at rest in a normalposition, said first blocking member movable on the actuation of saiduniversal bar to unblock said yieldable stop to permit the rotation ofsaid rotatable member, means operated by said rotatable member duringrotation thereof to move said yieldable stop to a stop position, asecond blocking member for holding said yieldable stop in said stopposition to prevent further rotation of said rotatable member, and meansfor rendering said second blocking member inoperative to permit thecontinued operation of said rotatable member.

11. In a telegraph keyboard transmitter, a rotatable member normallytending to rotate, a yieldable stop latch to hold said member againstrotation, a first blocking member for blocking yielding movement of saidstop latch, a set of key levers, a universal bar invariably operated onthe actuation of any of said key levers to move said blocking member andunblock said yieldable stop latch to permit rotatation of said rotatablemember, means associated with said rotatable member for moving saidyieldable latch to latching position after each one-half revolution ofsaid member, a second blocking member for said latch, means foroperating said second blocking member to block yielding movement of saidlatch when said first blocking member is held in its unblockingposition, thereby preventing further operation of said rotatable member,and means for rendering said first blocking member operative and saidsecond blocking member inoperative upon deactuation of said universalbar.

12. In a telegraph keyboard transmitter, a rotatable member normallytending to rotate, a yieldable stop latch normally holding said memberfrom rotation, a first blocking member for blocking yielding movement ofsaid stop latch, a set of key levers, a universal bar invariablyoperated on the actuation of any of said key levers to move saidblocking member to unblocking position and thereby release saidyieldable stop latch to permit rotation of said rotatable member, meansassociated with said rotatable member for moving said yieldable latch tolatching position after each one-half revolution of said member, asecond blocking member for said latch, means for operating said secondblocking member for blocking yielding'movement of said stop'latch tohold said rotatable member against continued rotation when said firstblocking member is held in its unblocking position, and means forrendering said second blocking member inoperable to permit continuedoperation of said rotatable member.

13. In a keyboard transmitter, a rotatable member, means to initiaterotation of said rotatable member, a plurality of contact operatinglevers, a pair of current transmitting'contacts common to said contactoperating levers, and means including one of said contacts engageable byand alternatively forced to move to the contact open and to the contactclosed position by actuation of said contact operating levers, meansincluding said rotatable member for sequentially actuating said contactoperating levers within a half revolution of said rotatable member tooperate said contacts in a predetermined mannor to transmit apredetermined code signal, and means associated with said rotatablemember and operable to stop rotation thereof at the end of .eachone-half revolution after said code signal has been transmitted.

14. In a telegraph printer, a rotatable member normally tending torotate, a yieldable stop latch normally holding said member fromrotation, a first blocking member for blocking yielding movement of saidstop latch, a

set of key levers, a universal bar invariably operated on the actuationof any of said key levers to move said blocking member to unblockingposition and thereby release said yieldable stop latch to permitrotation of said rotatable member, means associated with said rotatablemember for moving said yieldable latch to latching position afterone-half revolution of said member, a second blocking member for saidlatch resiliently connected to said first blocking member for movementtherewith to a position to block yielding movement of said stop latch tohold said rotatable member against continued rotation when said firstblocking member is held in its unblocking position, and means forrendering said second blocking member inoperable to permit continuedoperation of said rotatable member.

15. In a telegraph printer, a rotatable member normally tending torotate, a yieldable stop latch normally holding said member fromrotation, a first blocking member for blocking yielding movement of saidstop latch, a set of key levers, a universal bar invariably operated onthe actuation of any of said key levers to move said blocking member tounblocking position and thereby release said yieldable stop latch topermit rotation of said rotatable member, means associated with saidrotatable member for moving said yieldable latch to latching positionafter one-half revolution of said member, a second blocking member forsaid latch, resiliently connected to said first blocking member formovement therewith to a position to block yielding movement of said stoplatch to hold said rotatable member against continued rotation when saidfirst blocking member is held in its unblocking position, and meanscontrolled by actuation of at least one of said key levers for renderingsaid second blocking member inoperable to permit continued operation ofsaid rotatable member.

16. In a telegraph printer, a rotatable member normally tending torotate, a yieldable stop latch normally holding said member fromrotation, a first blocking member for blocking yielding movement of saidstop latch, a set of key levers, a universal bar invariably operated onthe actuation of any of said key levers to move said blocking member tounblocking position and thereby release said yieldable stop latch topermit rotation of said rotatable member, means associated with saidrotatable member for moving said yieldable latch to latching positionafter one-half revolution of said member, a second blocking member forsaid latch resiliently connected to said first blocking member formovement therewith to a position to block yielding movement of said stoplatch to hold said rotatable member against continued rotation when saidfirst blocking member is held in its unblocking position, and means forrendering said second blocking member inoperable to permit continuedoperation of said rotatable member comprising a member selectivelyoperative to engage said second blocking member in opposition to theresilient connection between said blocking members to prevent movementof said second blocking member to its blocking position.

17. A transmitting mechanism comprising a fixed transmitting contact, abail having a contact thereon and mounted for pivoted movement between afirst position of engagement of said bail contact with said fixedcontact and a second position of disengagement of said contacts, a setof bail operating levers disposed on the side of said bail opposite saidfixed contact and each mounted at one end for pivotal and radial slidingmovement relative to a common axis spaced from and parallel to the pivotaxis of said bail, a set of blocking latches permutatively settable tooperative and inoperative positions, said latches when in theiroperative position being effective to engage the free end of one of saidoperating levers, and a rotatable cam member provided with ofisetprojections on the periphery thereof operative upon rotation of saidmember to engage said levers sequentially intermediate their ends toimpart pivotal movement about said common axis to each leverunrestrained by a blocking latch .14 and pivotal movement about thenormally free endof each lever restrained by a blocking latch tovariably engage and disengage said contacts in accordance with thepermutatively setting of said latches.

18. A transmitting mechanism comprising a pair of fixed transmittingcontacts, a bail having a pair of contacts thereon and mounted forpivotal movement between :1 first position of engagement of one of saidbail contacts With one of said fixed contacts and a second position ofengagement of the other of said bail contacts with the other of saidfixed contacts, a set of bail operating levers disposed on the side ofsaid bail opposite said fixed contacts and each mounted at one end forpivotal and radial sliding movement relative to a common axis spacedfrom and parallel to the pivot axis of said bail, a set of blockinglatches permutatively settable to operative and inoperative positions,said latches when in their operative position being effective to engagethe free end of one of said operating levers, and a rotatable cam memberprovided with ofiset projections on the periphery thereof operative uponrotation of said member to engage said levers sequentially intermediatetheir ends to impart pivotal movement about said common axis to eachlever unrestrained by a blocking latch and pivotal movement about thenormally free end of each lever restrained by a blocking latch tovariably engage said contacts in accordance with the permutative settingof said latches.

19. A keyboard transmitting mechanism comprising a group of key levers,a set of permutation bar s variably positioned by actuation of said keylevers, a pair of fixed transmitting contacts, a bail having a pair ofcontacts thereon and mounted for pivotal movement between a firstposition of engagement of one of said bail contacts with one of saidfixed contacts and a second position of engagement of the other of saidbail contacts with the other of said fixed contacts, a set of bailoperating levers disposed on the side of said bail opposite said fixedcontacts and each mounted at one end for pivotal and radial slidingmovement relative to a common axis spaced from and parallel to the pivotaxis of said bail, a set'of blocking latches each individuallycontrolled by one of said permutation bars and each operative in oneposition to engage the free end of one of said operating levers, and arotatable cam member provided with ofi'set projections on the peripherythereof operative upon rotation of said member to engage said leverssequentially intermediate their ends to impart pivotal movement aboutsaid common axis to each lever unrestrained by a blocking latch andpivotal movement about the normally free end of each lever restrained bya blocking latch to variably engage said contacts in accordance with thesetting of said permutation bars.

20. In a telegraph transmitter, a set of permutatively settable pivotedblocking members each operable to one of two alternative positionsindicative of a signal to be transmitted, a set of contact operatinglevers each normally pivotally mounted adjacent one end and each adaptedto pivotally coact at its other end with an aligned one of said pivotedblocking members when in one of said alternative positions to berestrained against pivotal movement about said one end, a pair oftransmitting contacts common to all of said contact operating levers,and a rotatable cam member operative to engage said levers intermediatetheir ends and to sequentially pivot each of said contact operatinglevers about one of its ends in accordance with the variable positionsof said blocking members to variably operate said pair of transmittingcontacts according to the signals to be transmitted.

21. In a telegraph transmitter, an independently rotatable member, aseries of contact operating levers each having two alternativelyselectable oppositely directed paths of motion, movable means, includinga pair of current controlling contacts common to said series of contactoperating levers forced to move in one direction to close said contactsby movement of a contact operating lever in one of its paths of motionand forced to move in the contact opening direction by movement of acontact operating lever in the other of its paths of motion, meansoperable by said rotatable member to sequentially actuate said contactoperating levers in one of their said paths of motion, and a pluralityof permutatively settable means for restraining the movement of aselected group of said contact operating levers in said first path ofmotion and to compel the movement thereof in a second path of motionwhereby said pair of contacts is actuated in a predetermined manner tocorrespond to the permutative setting of said permutatively settablemeans.

22. A permutation keyboard mechanism comprising a group of key levers, aset of permutation bars variable positioned by actuation of said keylevers, a set of pivoted blocking members each operated by saidpermutation bars to one of two alternative positions, a set of contactoperating levers each normally pivotally mounted adjacent one end andeach adapted to pivotally coact at its other end with an aligned one ofsaid pivoted blocking members when in one of said alternative positions,a pair of transmitting contacts common to all of said contact operatinglevers, and a rotatable cam member to sequentially operate each of saidcontact operating levers about one of its ends in accordance with thevariable positions of said blocking members to variably engage said pairof transmitting contacts according to the signal to be transmitted.

23. In a telegraph keyboard: a set of key levers; a universal barinvariably operated upon actuation of any one of said key levers; apower driven rotatable member; a yieldable stop; a first blocking memberfor said stop; means including said yieldable stop and said firstblocking member for holding said rotatable member at rest in a normalposition, said blocking member being movable on the actuation of saiduniversal bar to unblock said yieldable stop to permit the rotation ofsaid rotatable member; means operated by said rotatable member duringrotation thereof to move said yieldable stop to a stop position; meansincluding said first blocking member and a second blocking memberrendered operative when said universal bar is retained in actuatedposition during rotation of said rotatable member for holding saidyieldable stop in said stop position by said second blocking member toprevent further rotation of said rotatable member and upon deactivationof said universal bar for rendering said first blocking member operativeto hold said rotatable member at normal rest position and removing saidsecond blocking member from its blocking position.

24. A telegraph printer comprising: a rotatable member; means forrotating said member; a plurality of rockable blocking members; a pairof contacts comprising a movable contact, a second contact, a supportfor said second contact, a support for said second contact adjustable toregulate the normal relationship of said contacts, and resilient meansassociated with said second contact and said support for absorbing theshock of contact engagement and preventing undesirable disengagement ofsaid contacts; and a set of contact operating levers having twovarieties of motion controlled by said blocking members in predeterminedcombinations and sequentially operated by said rotatable member toengage and disengage said contacts, said contacts being common to all ofsaid contact operating levers.

References Cited in the file of this patent UNITED STATES PATENTS1,090,816 Henschel Mar. 17, 1914 1,229,201 Potts June 5, 1917 1,496,875Field June 10, 1924 1,545,276 Pfannenstiehl July 7, 1925 1,849,403Jefierson Mar. 15, 1932 1,884,807 Morton Oct. 25, 1932 2,167,528 SalmonJune 24, 1941 2,247,162 Beccio June 24, 1941 2,522,461 Potts Sept. 12,1950 2,533,397 Peter Dec. 12, 1950

